Few urban areas are taking the necessary steps to protect their residents – billions of people around the globe – from such likely events as heat waves and rising seas, according to research to appear in Current Opinion in Environmental Sustainability and European Planning Studies.

They are also failing to cut their own emissions of climate-warming greenhouse gases, the study found.

“Climate change is a deeply local issue and poses profound threats to the growing cities of the world,” study author Patricia Romero Lankao, a sociologist specialising in climate change and urban development, said in a statement.

Because half of Earth’s population is in cities, scientists like Romero Lankao are focusing on the potential climate change impacts in these areas.

Air pollution

The mere fact that they are cities, with densely packed construction, places their populations at greater risk from natural disasters, including those expected to be made worse by climate change.

Storm surges can inundate heavily populated coastal areas and heat waves can warm up paved cities more than surrounding areas, Romero Lankao found. And these events can be amplified in an urban environment.

In cities, prolonged hot weather can exacerbate existing levels of air pollution, causing health problems. Poorer urban neighbourhoods that lack reliable sanitation, drinking water or roads are at increased risk, according to Romero Lankao, of the US National Centre for Atmospheric Research.

The number of city-dwellers worldwide has quadrupled since 1950, the study found, projecting that by 2020, more than 500 urban areas will have a million residents or more.

But urban leaders are largely failing to prepare for coming natural disasters that could affect their people, including building public transport that would cut greenhouse emissions, Romero Lankao said.

“Cities can have an enormous influence on emissions by focusing on mass transit systems and energy efficient structures,” she said. “But local leaders face pressures to build more roads and relax regulations that could reduce energy use.”

She noted that some cities’ efforts to cut emissions are part of a larger push to ease traffic and other problems. She cited central London’s Congestion Charging Zone, which aims to encourage more use of public transit, as one example. In Latin America, Curitiba, Brazil, and Bogota, Colombia, are integrating new development with mass transit systems.

Romero Lankao’s study was conducted in association with the UN Human Settlements Program and funded by the US National Science Foundation.